Abstract:
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Purpose: To investigate the extent of white matter tissue damage of patients with Alzheimer's disease (AD) in comparison with healthy subjects using diffusion tensor MRI (DTI).
Methods and Materials: We studied 15 patients and 16 age and gender matched healthy controls. DTI brain scans were obtained on a 1.5 Tesla magnet (Siemens Magnetom Sonata) using parallel imaging (iPAT) and an EPI diffusion sequence with TE/TR 71 ms/6000 ms. We used an 8-element head coil and a GRAPPA reconstruction algorithm with an acceleration factor of 2. Voxel size was 1.8 x 1.8 x 3.6 mm3. The diffusion tensor was calculated from images acquired with diffusion gradients applied in six non-collinear directions and b values of 0 and 1000 sec/mm2. From the tensor, the mean diffusivity (D), the fractional anisotropy (FA), and the relative anisotropy (RA) of several white matter regions were determined.
Results: D was significantly higher in the white matter of the frontal lobes from patients with AD than in the corresponding regions from healthy controls (p<0.01). We found only slight changes of RA and FA between patients and controls for the other regions studied. The images obtained with iPAT contained substantially less susceptibility artifacts and were less distorted than images acquired with non-parallel imaging technique.
Conclusion: DTI is a method with potential to assess early stages of white matter damage in vivo. The increased D values in the frontal lobe of patients with AD presumably reflect the microscopic white matter degeneration. iPAT methods accelerate the acquisition time and yield images with less distortion due to susceptibility artifacts and thus allows for a more accurate calculation of the diffusion tensor. Therefore, applications which are based on tensor estimation like fiber tracking can be performed with higher precision.
Questions about this event email: Robert.Stahl@ikra.med.uni-muenchen.de
Stahl MD, R,
Assessment of White Matter Damage in Alzheimer's Disease with Diffusion Tensor MRI Using Parallel Imaging Technique. Radiological Society of North America 2003 Scientific Assembly and Annual Meeting, November 30 - December 5, 2003 ,Chicago IL.
http://archive.rsna.org/2003/3105444.html
